Abstract: Dynamic thermal characteristics of sealing film for T-grooves gas face seals were investigated considering thermal and elastic distortions. Dynamic fields of gas film pressure and temperature were presented at different perturbation frequencies. Then dynamic coefficients of gas film stiffness and damping as well as the amplitude-frequency characteristic was numerically calculated with the perturbation method. Results show that thickness of sealing film decreased significantly due to the elastic and thermal distortions of seal faces at high seal pressure and speed. Ambient perturbation generated additional distributions of pressure and temperature. With the increase of perturbation frequencies, the dynamic coefficient of stiffness increased sharply while the dynamic coefficient of damping decreased. The amplitude perturbation presented a logarithmic increase with increasing perturbation frequency in a range of perturbation frequencies, and the damping induced from the second seal made the amplitude increase sharply.